1. Field of the Invention
This invention relates to clocks for a network, and in particular to methods and systems for multiple clocks for ports on a hub.
2. Description of Related Art
Computer networks are called upon to handle increasingly higher speeds of data transmission. Computer networks often involve numerous end stations coupled together in a hub for communication with each other. Such hubs may represent a bottleneck for efficiency in transmission between the various end stations or other elements of the network. A hub often includes a number of ports, which are coupled to the end stations or other devices in the computer network. Ports are then coupled to other ports via a bus within the hub. Some hubs used in computer networks are repeating hubs and others are switching hubs.
Within the hub, ports must transmit and receive onto the common bus. Conflicts may occur when the various ports attempt to simultaneously transmit from the same bus. One system for resolving conflicts between entities sharing a common transmission medium is the carrier sensed multiple access with collision detect (CSMA-CD) scheme. Under such a scheme, entities attempting to transmit over the shared medium attempt to transmit over the medium and if a conflict occurs then the entities do not transmit at that time. Such a scheme may involve inefficiencies in the use of the transmission medium. More efficient and robust systems for sharing media such as a bus within a hub are needed.
As computer networks increase in speed, components within network devices may be called upon to operate at higher speeds. Clocks for controlling operation of such high speed components are important. However, physical limitations of a bus may prevent the bus from running at a desired clock speed.